This invention relates to adjustable switch point guard rails for use adjacent the switch point of railway switches in trackwork. It relates specifically to adjustable guard rails having a surface for engaging and laterally urging the moving wheels of rolling stock in a direction toward the centerline of the trackwork where the wheel engaging surface is capable of adjustment to a variety of positions toward or away from the switch point of the trackwork.
The switching rail of a railway switch assembly includes a tapered rail portion which terminates into a thin end point for intercepting and switching the wheels of rolling stock from one rail onto another. To prevent the wheels of the rolling stock from damaging these thin end portions of the switching rails, guard rails are used to engage and urge the wheels in a lateral direction toward the centerline of the trackwork. This lateral displacement of the wheels avoids contact between the wheel flanges and the thin end of the tapered section of the switching rail and transfers the initial contact between the wheels and switching rail to some point along the rail where the rail section is thicker.
Because such switch point guard rails experience considerable wear due to the repeated contact between the moving wheels and the wheel engaging surface of the guard rail, and, because proper placement of the guard rail with respect to the switch point is critical, it is desirable to provide means to adjust the switch point guard rail toward or away from the switch point. Such adjustment means enables initial proper placement of the guard rail adjacent the switch point and later adjustment as the wheel engaging surface is worn away by the wheels.
Adjustable switch point guard rails have been used in the past to extend guard rail life. U.S. Pat. Nos. 4,738,418 and 4,386,751, granted to Farrell and Meyer respectively, disclose adjustable switch point guard rails. However, these patents disclose adjustment to a predetermined, limited number of lateral adjustments. Farrell provides three fixed adjustment positions while Meyer provides only two such adjustments. The predetermined, fixed adjustment positions shown in both of the prior patents greatly limits the precision of the guard rail adjustment means and both inventors fail to provide fine, accurate, positioning of the guard rail with respect to the switch point of the railway switch. In addition, because the adjustment means shown in the two prior patents provide only one and two fixed, predetermined, guard rail wear adjustments, the service life of the adjustable guard rail is greatly limited. In order to overcome the aforementioned limitations of prior adjustable guard rails, an adjustable guard rail assembly must include means for adjusting and fastening the adjustable guard rail to a variety of positions toward or away from the switch point within a given range of lateral movement.